‘Mr Putin understands the power of asymmetric reactions. But the west, too, has options in reserve.’
Photograph: Mikhail Svetlov/Getty Images

Whatever the balance of motives in the attempted murder of former Russian spy Sergei Skripal – and these may never be precisely ascertained – one consideration is likely to have been key. This is the weakness of the UK, which decided against a strong response to the fatal poisoning of Alexander Litvinenko, is planning its exit from the European Union and is trying to manage a transatlantic relationship that looks less special than ever. Britain, like other US allies, must deal with an unreliable American president who has displayed extraordinary sympathy for his Russian counterpart, and whose campaign is under investigation for possible collusion with the Kremlin.

These measures are in large part symbolic. Though they will likely damage Russian intelligence-gathering, they do not cover those who are spying without diplomatic cover. Some of the countries involved are expelling a single official. Only half of the EU’s members are acting and there are notable omissions: most glaringly Austria, which says it is “a neutral country” and wants to remain a “bridge-builder” between east and west, keeping communications channels open.

Nonetheless, the breadth of this response is much greater than might have been anticipated. Moscow has sought to fracture the west and undermine multilateralism. This display of unity is to the credit of the prime minister and the Foreign Office, who have achieved it despite the counterproductive posturing of the foreign and defence secretaries.

Theresa May’s foreign counterparts have proved more helpful, despite the concerns that key players such as France might be reluctant to sign on. The joint statement from the US, UK, Germany and France, saying there was “no plausible alternative explanation” for the poisoning, was the turning point. Allies have acted from sensible national interest. The collective message both indicates anger at Russian actions targeting them in recent years – such as cyberattacks – and puts down a marker. Unleashing a chemical weapon on the streets of a city is hardly a marginal issue; it crosses a line few would want to ignore. The brazenness of Moscow’s reaction further helped Mrs May.

No measures are cost-free; these do close off already limited channels. They may, if anything, bolster domestic support for Mr Putin’s claims that Russia is ringed by hostility. Few in Russia appear to believe that Moscow was responsible – and in any case they are far more preoccupied by the horrific fire in Siberia. They will doubtless be followed by tit-for-tat expulsions, and probably something more: Mr Putin understands the power of asymmetric reactions. But the west, too, has options in reserve.

A critical question will be whether they involve targeting the assets of Mr Putin’s oligarch friends. There are complaints elsewhere that London, even as it seeks support from allies, is reluctant to pay too high a price for challenging Moscow. Mr Trump last week congratulated the Russian president on his re-election against explicit advice, and did not raise Mr Skripal’s case. And, prior to the poisoning, a “name-and-shame” list of corrupt Russian oligarchs with ties to Mr Putin was replaced at the last minute with an all-inclusive list of rich Russians apparently cribbed from Forbes. Maintaining any kind of unity of response in these circumstances will be extremely difficult. But in a world of imperfect options, this week’s measures have sent an important message.